Economy Minister Michael Glos at the same time called on Moscow and Kiev "to find without delay" an acceptable solution to their dispute over payment.
"German gas distributors prepared carefully for just such an eventuality. All necessary measures have been taken so as to be able to react appropriately in case" Russian gas supplies transiting via Ukraine are disrupted," Glos said in a statement.
He said commitments had been given that Russian gas deliveries to third countries should not be called into question.
"Bilateral problems should not jeopardise" such commitments, he said, adding that Germany had large gas stocks and a diversified supply base.
Russia earlier Thursday halted gas supply to Ukraine after the two ex-Soviet neighbours failed to agree on payment terms.
Ukraine's gas company, Naftogaz, separately confirmed that the volume of gas it was receiving from Russia had dropped, but promised that transit of supplies meant for customers downstream in Europe would be guaranteed.
A similar dispute between Russia and Ukraine in 2006 led to disruption of supplies to Western Europe, which relies on Moscow for a quarter of its gas.